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I have a 351W, trick flow heads, edelbrock Performer RPM manifold, Holley Averger 670 cfm carb. What happens is----- I start the car when it is cold and the fuel pressure goes right up to 6 pounds. I have a Jeg's gauge mounted by the carb. After 10 minutes of idleing the pressure starts to drop to 1-2 pounds and air forms in the clear fuel filter about 1 foot from the carb. So I bought a Carter high volumn mechanical pump. Same problem. So I bought an Edelbrock 110 gph mechanical pump and insulated the pump and the fuel line. Same problem. So I spent $350 on AN-8 stainless steel braided line with a Fram racing fuel filter and a Holley blue electric pump. Mounted the pump and filter by the gas tank as per the instructions. Wow is that thing loud!!! Well I fired it up, adjusted the regulator to 6 psi and guess what. Same problem!!! Is the gas boiling in the carb or what? I then let the car cool down and I ran the electric pump for 10 minutes without starting the car. The pressure held perfectly. Help please. I would like to be able the run the juice that has been sitting in the trunk laughing at me. I have the nitrous plate below the carb and nothing else.
 

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Sounds like fuel percolation to me. I'd spring for a carb insulator/spacer and see if that doesn't help. Whole lot cheaper than what you've already done...
 

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Discussion Starter #3
What blows me away is that it happens with the hood up. And I have a high flow fan. Or doesn't that matter. Is it maybe the heat transfer from the manifold through the nitrous plate to the carb?
 

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May sound dumb, but try loosening up the gas cap. If you have a non-vented cap on a gas tank that requires a vented one you will build up a vacuum and the pump won't be able to pull the fuel out of the tank. If you run the pump with the engine off it will just deadhead since it is not actually pumping anything, just recirculating the fuel through the pump. Also, there is no way any pump should be starving an engine at idle, there is just no demand for fuel.
 

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Sounds to me like your sucking air somewhere along the line. How old is the tank in the car and are you sure it's filled to the brim before you start and run it?
 

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I have nearly the same problem with my car. I have a 302 in my T-Bird with a performer plus carb and intake set up. I installed a clear fuel filter and also noticed that my filter was never more than about half full. The fuel was spurting into the filter very erratically at times but then I would shut it off and upon starting it back up it would work almost fine. I figured the pump was still stock and simply was shot. I started by replacing the stock fuel pump with a mechanical Carter street pump and ran 3/8" fuel line from the pump to the carb. I found that this was making no difference, the filter was still not filling more than about half way. I then added a fuel pressure gauge from Summit. The gauge showed that my pressure was initally about 2lbs too high. I adjusted it to about 7lbs. and it seemed to do the trick. A day or so later I found that the pressure had dropped to about 5.5lbs. I adjusted it on a few more occasions and then realized it was drawing air, evident by the erratic spurting and constantly different pressure at idle. I found that the supply line hose comming off the tank had dry rotted/cracked and was damp with fuel. I replaced it with some braided hose. It seems to have helped for the most part, however I still notice the occasional loss of fuel pressure and slightly lower levels of fuel in the inline filter. I noticed that if I run the car for a few minutes it will show a different fuel pressure than if I shut it off and start it up again. I think that I may have something in my fuel thank that is blocking the constant even flow of fuel(22 years of dirt, an old sock... who knows) Anyway my next step and one you might consider, is dropping the fuel tank and having a look in there for any thing that may be clogging up the pick up assembly. Just my 2cents...
 

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Well, heres my $0.02 worth. I believe it may be the glass filter, which are dangerous.They do not seal properly and I have seen them crack and shatter and start fires. Many years ago, we built a couple of cars to do stunts with in a movie. One of my mechanics put a glass filter on the Camaro he had rigged to do a high speed chase while my other mechanic and I set up LTD. The first time the stunt guy went around the corner, the filter cracked and spewed gas all over. Thankfully there hadn't been a spark or a crash. Jerry Valentine from NHRA Tech willfail any car that arrives for tech with a glass fuel filter. I know, some of you have sneaked them pass but they really are not safe.
 
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